At present almost all therapy for pollen allergies and other allergic diseases consists of symptomatic treatment with antihistamines, but recently desensitization therapy has gained attention as a mode of therapy that can be completely cured cause of an allergic disease.
Because desensitization therapy generally requires long-term administration of approximately 2 to 3 years, a dosage form that will more greatly improve the quality of life (QOL) of both caregivers and patients is needed.
At present, almost all the dosage forms used in specific desensitization therapy are injectables intended for subcutaneous injection.
However, the following problems occur with specific desensitization therapy utilizing subcutaneous injections: there is a danger of anaphylactic shock, administration must be made by a healthcare provider, the patient must make frequent visits to the healthcare provider over a long period of time, there is pain associated with the injection, and the injectable preparations must be stored under refrigeration.
In contrast, liquid and tablet preparations for sublingual administration have been marketed in Europe and the United States in recent years, and they have garnered attention because they cause few adverse reactions and they are easy to use.
There have been problems with specific desensitization therapy utilizing sublingual administration of liquid preparations, however, because the dose is imprecise, the preparations require storage under refrigeration, and the like.
A solid vaccine comprising a lyophilisate comprising an oxygen-containing metal salt, an antigen, and one or more excipients selected from saccharides, sugar alcohols, and amino acids or pharmaceutically acceptable salts thereof (Japanese Translation of PCT Application No. 2009-510136), and a fast-dispersing, non-compressed solid dosage form comprising a matrix and at least one allergen (Japanese Translation of PCT Application No. 2006-513269), etc., have been proposed as a tablet or other solid preparation containing an allergen.
There have been problems with specific desensitization therapy utilizing sublingual administration of a tablet, however, because the patient can swallow the tablet by mistake, it is difficult to fine-tune the dose, the portability is poor, the residue causes an unpleasant sensation in the mouth, and the like.
Therefore, one option that comes to mind as a method to address these problems is a film-form preparation that readily dissolves in the mouth.
A film-form preparation containing allergen wherein an active substance such as an allergen is dispersed or dissolved in a water-soluble polymer are already known. Examples include a film with non-self-aggregating uniform heterogeneity and method for preparing the same (Japanese Translation of PCT Application No. 2005-511522); a fast-dissolving film free of added plasticizer that contains at least one type of water-soluble polymer comprising polyethylene oxide alone or in combination with a hydrophilic cellulose polymer (Japanese Translation of PCT Application No. 2007-500252); and an autonomous, edible film for delivery of an active ingredient comprising an edible, water-soluble polymer, an anti-tacking agent, and an active substance (Japanese Translation of PCT Application No. 2009-507854).
A film-form preparation containing an allergen needs to have very little gummy sensation when placed in the mouth and very little sticky sensation when touched by the fingers.
As methods for reducing the gummy sensation and sticky sensation, a film-form preparation wherein a non-reducing sugar and a sugar alcohol are formulated thereinto is already known, and previous film-form preparation referred to allergens, wherein a non-reducing sugar and a sugar alcohol are formulated thereinto has been reported.
However, previous film-form preparations are those wherein the active substance such as an allergen are dispersed or dissolved in a water-soluble polymer. Therefore, water or a mixture thereof is used as the solvent in the manufacturing process, and the added sugars and sugar alcohols are in a dissolved or recrystallized state in the manufactured film-form preparation.
Thus, with previous film-form preparations it has been impossible to fully satisfy the film properties related to a gummy sensation when placed in the mouth, a sticky sensation when touched by the fingers, and high film strength merely by the addition of a sugar or sugar alcohol, and particularly a large amount of sugar or sugar alcohol. In addition, previous film-form preparations have not been considered optimal for patient desensitization therapy using an allergen because it has been almost impossible to intentionally control the dissolution time in the mouth.